1. Field
The present disclosure relates generally to signal processing and analysis. Still more particularly, the present disclosure relates to identifying undesired signals resulting from ambient emissions in desired test signal data.
2. Background
Interference to aircraft radio receivers is an increasing concern as more portable electronic devices are allowed on-board aircraft for use by passengers and crew in a cabin of the aircraft. To reduce this concern, potential interference signals may be attenuated as they propagate from electronic devices inside the aircraft cabin to aircraft radio antennas mounted on the outside of the aircraft. The level of this attenuation level may be referred to as an interference path loss value.
Interference path loss measurements may be performed on aircraft to determine whether the attenuation of signals between electronic devices in the cabin and the aircraft radio receivers is sufficient. Such measurements may be made, for example, by transmitting a test signal from within the cabin and analyzing the resulting test signal data received by the aircraft radio receivers.
The accuracy of such interference path loss measurements may be affected by ambient radio frequency emissions in the area where the measurements are made. For example, such ambient emissions may include terrestrial radio frequency communications in the area where the interference path loss measurements are made.
Ambient emissions may affect any test or measurement in which a test signal is intentionally transmitted from a transmitter and a resulting test signal received by a receiver is analyzed. In any such test, signals from ambient emissions may be received by the receiver along with the intentionally transmitted test signal. In this case, the ambient emissions may mask the test signal generated by the transmitter. The test signal data received by the receiver may include data resulting from received ambient emissions, thereby affecting the analysis of the test signal data in undesired ways. Therefore, a reliable analysis of the received test signal data set may not be made if the test is performed in the presence of ambient emissions.
The effect of ambient emissions on interference path loss measurements and other tests involving transmitting and receiving a test signal may be reduced by conducting the tests or other measurements in an area where ambient emissions are known to be at a reduced level. However, conducting such measurements or other tests under such controlled conditions may be expensive, inconvenient, time-consuming, or impractical in many cases.
Accordingly, it would be desirable to have a method and apparatus that takes into account one or more the issues discussed above, as well as possibly other issues.